Antacid: Antacids are used to help with heartburn, upset stomach, acid indigestion, and sour stomach, because they counteract the effects of extra stomach acid. That spicy enchilada and fifth margarita sounds like a good idea until your stomach can't handle it, and then you'll be glad you brought your Tums
Antihistamine: Antihistamines are very useful for reducing allergic reactions and inflammation, and their uses stem beyond alleviating traditional allergies. Especially when traveling, you never know when you will encounter something new to which you are allergic, or when you will develop a reaction to something common, like the sun! Antihistamines can also alleviate the symptoms associated with insect bites, stings, and sunburns.
Diarrhea medicine: Diarrhea medicine can feel like a life saver, and there is debate on whether one should take it, since some believe your body needs to expel whatever is in the body. However, diarrhea can also lead to dehydration, and most would agree that stopping diarrhea is vital to stopping dehydration. Diarrhea medicine can also alleviate the feelings of dizziness and stomachaches associated with traveler's diarrhea.
Tweezers: Tweezers are one of the many things we take for granted in our medicine cabinets at home, but as soon as you have a painful splinter or ingrown hair, you'll wish you had them with you. They take up virtually no room nor weight in your bag, so there is no reason to leave on a trip without a pair.
Sleeping Aid: If you have difficulty sleeping at home, this may be magnified while trying to sleep on planes and foreign hotel beds. Perhaps nothing is more frustrating, nor makes you feel more haggard, than enduring a long flight when you simply cannot sleep. Consult your doctor for one that is right for you. As an alternative to hard core sleep aids, three to five milligrams of Melatonin may be all you need to kick start your sleep. Melatonin is naturally found in the body and has other health benefits as well; for instance, it even helps your body acclimate faster to new time zones.